A hydrocarbon recovery well may be drilled by rotating a drill string, which is an assembly that generally includes a plurality of interconnected drill pipe segments having a drill bit and bottom hole assembly (“BHA”) at a lower end. As the well is drilled, the drill bit generates cuttings and other debris. In downhole drilling operations, fluid circulation is commonly used for wellbore cleaning and solids transport, such as to remove the cuttings and other debris. In general, circulation involves pumping fluid down the drill string (using a mud pump at the surface) and back up the annulus between the drill string and a wellbore wall. The speed at which the fluid moves along the annulus is referred to as the annular velocity. Thus, it is important to monitor the annular velocity to ensure proper wellbore cleaning, solid transport, as well as to avoid erosion of the wellbore wall.
The fluid annular velocity is adversely affected in a number of ways. For example, during circulation, pressure drops occur in the circulating system due to frictional losses inside the tubing and the annulus, as well as the differential hydrostatic pressure between the tubing and annulus. The maximum pressure is generated at the mud pump manifold (the standpipe pressure (“SPP”)) and the lowest pressure is generated at the fluid returns (atmospheric pressure for open returns or applied choke pressure for managed pressure operations). Thus, the fluid velocity is limited by the maximum SPP. As a result, in some instances, the annular velocity may not be high enough to sufficiently clean the wellbore. However, if the fluid pressure is somehow increased during circulation, the SPP can be reduced. In turn, this would permit an increase in the maximum pump rate which produces higher annular velocities.
Accordingly, in view of the foregoing, there is a need in the art for a method to increase the fluid annular velocity.